app: integrate interrupt forwarding

This significantly increases usability of command line tools running through hakurei.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/container_linux.go

@@ -32,6 +32,10 @@ func newContainer(s *hst.ContainerConfig, os sys.State, uid, gid *int) (*contain
 		SeccompPresets: s.SeccompPresets,
 		RetainSession:  s.Tty,
 		HostNet:        s.Net,
+
+		// the container is canceled when shim is requested to exit or receives an interrupt or termination signal;
+		// this behaviour is implemented in the shim
+		ForwardCancel: !s.ImmediateTermination,
 	}
 
 	{